Answer
$43,800,000 = 4.38\cdot 10^7$
Work Step by Step
STEP $1$:
On October $28$, $2020$, the number of people who are Covid-$19$ positive around the world is $43.8$ million.
STEP $2$:
The number $43.8$ million can be expressed as: $43,800,800$
STEP $3$:
Convert the number in scientific notation: $43,800,000 = 4.38\cdot 10^7$
STEP $4$:
At the same time, the population of the people around the world is $7.83$ billion.
STEP $5$:
Comparing the number of Covid-$19$ positive and the world population, the number of Covid-$19$ positive is relatively small.
